Presumably there is a video buffer somewhere which will display any pixels that you choose to put there, without there being any activity from the GPU part of the video controller?
How is its area, frame rate and X and Y pixel range determined?
Also, for dynamic video such as DVB there must be some means of instructing the graphics processor how to overwrite that area?
Has there been published any disassembly of the graphics library to work out what is going on so that 64 bitters could drive it from A64?
Yours etc, Confused from Tunbridge Wells